Practical Electron Microscopy and Database

An Online Book, Second Edition by Dr. Yougui Liao (2006)

Practical Electron Microscopy and Database - An Online Book

Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix

Σ(Sigma Number): Coincident-Site-Lattice (CSL) of Twin and Grain Boundaries

The Coincident Site Lattice (CSL)is a useful concept for identifying boundaries with low misfit as well as low energy. For instance, two FCC lattices rotate about [110] by an angle θ and allow to interpenetrate through each other to form a dichromatic boundary. At some angles θ, the pattern contains sites shared by both lattices. At such angles, the coincident sites themselves form a lattice, named as CSL, which for the [110] axis is base-centered orthorhombic. The CSL is characterized by the number of sites, Σ (sigma number), of each lattice per coincident site.